Gas turbine exhaust passage and damper system for same

Abstract

A gas turbine exhaust passage is realized which may suppress the radiation of strong ultra low frequency noise to the outside without amplifying the turbulence of an high speed exhaust gas flow rate or a pressure pulsation generated in a gas turbine. At least a portion of a wall of a gas turbine exhaust passage ( 3, 5 ) is formed of an acoustically transmissive material ( 36, 56 ) for allowing a low frequency noise of several tens of Hz or less to pass therethrough sufficiently. Also, the acoustically transmissive material is made of one or more of a porous material, a porous heat insulating material, a mesh having a large flow resistance, cloth or film material. Further, the acoustically transmissive material is supported by a porous plate or a frame. In a case where an acoustically transmissive material is used only for an exhaust chimney ( 5 ), the exhaust chimney ( 5 ) is supported by a rack ( 11 ). Further, a soundproof panel ( 12 ) may be attached to the rack ( 11 ). Also, a damper provided at a branch portion between an exhaust gas boiler branched from the gas turbine exhaust passage and the gas turbine exhaust passage is formed of acoustically transmissive material for allowing a low frequency noise of several tens of Hz or less to pass therethrough sufficiently.

1. The damper system for a gas turbine exhaust passage, comprising:
 a gas turbine exhaust passage for discharging exhaust gas of a gas turbine, an exhaust boiler branched from said gas turbine exhaust passage, and a damper provided at a branch portion between said exhaust boiler and said gas turbine exhaust passage, wherein said damper is made of an acoustically transmissive material that may sufficiently transmit a low frequency noise of several tens of Hz or less, wherein said acoustically transmissive material is porous and is disposed from one outermost portion to the other outermost portion of the damper across a thickness direction of the damper, 
 wherein said acoustically transmissive porous material is made of at least one material selected from the group essentially consisting of porous heat insulating material, mesh having a large flow resistance, cloth and film material. 
 
   
   
     2. The damper system for a gas turbine exhaust passage, according to  claim 1 , wherein the acoustically transmissive porous material is supported by a porous plate or frame. 
   
   
     3. A damper system for a gas turbine exhaust passage, comprising an exhaust duct connected to a gas turbine body through an exhaust diffuser and provided with an internal exhaust silencer, a bypass chimney connected to said exhaust duct, an exhaust gas boiler branched at a branch portion from said exhaust duct, and a damper provided between said exhaust gas boiler and said exhaust duct, wherein said damper is formed of an acoustically transmissive material for allowing a low frequency noise of several tens of Hz or less to pass therethrough sufficiently, wherein said acoustically transmissive material is porous and is disposed from one outermost portion to the other outermost portion of the damper across a thickness direction of the damper,
 wherein said acoustically transmissive porous material is made of at least one material selected from the group essentially consisting of porous heat insulating material, mesh having a large flow resistance, cloth and film material.